Chemical biorefinery perspectives : the valorisation of functionalised chemicals from biomass resources compared to the conventional fossil fuel production route

In response to the impending problems related to fossil fuels (continued supply, price, and regional and global pollution) alternative feedstocks are gaining interest as possible solutions. Biomass, considered sustainable and renewable, is an option with the potential to replace a wide diversity of fossil based products within the energy sector; heat, power, fuels, materials and chemicals. All the proposed applications for biomass, however, require direct and indirect fossil derived inputs. The maximum fossil fuel replacement potential of various biomass systems and biorefinery concepts were determined using life cycle analysis (LCA) tools. Yet, as opposed to a traditional LCA, the calculation matrix developed here revolves around energy flows and was extended to incorporate process efficiency in terms of exergy, essentially compiling a comparative exergetic cradle-to-factory gate analysis. Inclusion of exergy calculations requires a greater understanding of the processes and reveals that several previous assumptions towards agricultural systems are no longer suitable for non-biomass applications. It also revealed that by upholding the functionality of the biochemicals present in biomass for use as chemical products and precursors, sizeable reductions of fossil fuels can be achieved. Oriented towards existing bulkchemical products, the analysis was expanded to systematically determine the optimal biorefinery cropping system from 16 common bioenergy crops in their corresponding regions. Although no concrete optimum was determined, the results all led to the conclusion that other biomass systems based on combustion or conversion to combustible products are sub-optimal in comparison. The best application of biomass for the replacement of fossil fuels is the petrochemical industry.